Problem: The grades on a history midterm at Loyola are normally distributed with $\mu = 85$ and $\sigma = 4.0$. Christopher earned a $94$ on the exam. Find the z-score for Christopher's exam grade. Round to two decimal places.
Explanation: A z-score is defined as the number of standard deviations a specific point is away from the mean We can calculate the z-score for Christopher's exam grade by subtracting the mean $(\mu)$ from his grade and then dividing by the standard deviation $(\sigma)$ $ { z = \dfrac{x - {\mu}}{{\sigma}}} $ $ { z = \dfrac{94 - {85}}{{4.0}}} $ ${ z \approx 2.25}$ The z-score is $2.25$. In other words, Christopher's score was $2.25$ standard deviations above the mean.